JP7432558B2 - Inspection equipment and inspection method - Google Patents

Description

The present invention relates to an inspection device and an inspection method.

A known method for determining whether a group of light emitting elements formed on a substrate is good or bad is probing, which measures the light emission (electroluminescence) produced when a needle is placed on a light emitting element and electricity is passed through it. However, with respect to minute light emitting elements such as μLEDs formed on a wafer, probing, which involves placing a needle on each of the plurality of light emitting elements for measurement, is physically difficult. As another method, a method is known in which the quality of the light emitting element is determined by, for example, irradiating the light emitting element with excitation light and observing photoluminescence emitted by the light emitting element (see, for example, Patent Document 1). According to this method, it is possible to efficiently determine whether fine light emitting elements such as the above-mentioned μLEDs are good or bad.

JP2018-132308A

Here, in the method of determining pass/fail by observing photoluminescence, it is required to appropriately acquire (observe) the light emitted from the light emitting element to be measured and to judge the pass/fail of the light emitting element with high precision. There is.

The present invention has been made in view of the above circumstances, and an object of the present invention is to highly accurately determine the quality of a light emitting element.

An inspection apparatus according to one embodiment of the present invention is an inspection apparatus for inspecting an object having a plurality of light emitting elements formed on a substrate, and includes a light source unit that generates excitation light to be irradiated to the light emitting elements, and a light source unit that generates excitation light to irradiate the light emitting elements; a light detection unit that detects the light emission of the light emitting element irradiated with the light emitting element; an input unit that receives information regarding the emission color of the light emitting element; and determining the wavelength of the excitation light based on the information regarding the emission color received by the input unit; a control unit that controls the light source unit so that excitation light of the wavelength is generated, the control unit configured to generate excitation light that is longer than the absorption edge wavelength of the target substrate and that is specified from information regarding the emission color. A wavelength shorter than the peak wavelength of the emission spectrum of the device is determined as the wavelength of the excitation light.

In the inspection apparatus according to one embodiment of the present invention, input of information regarding the emission color of the light emitting element is accepted, and the wavelength of the excitation light is set to be a wavelength shorter than the peak wavelength of the emission spectrum of the light emitting element. In this way, the wavelength of the excitation light is determined according to the emission color of the light emitting element, and by making the wavelength of the excitation light shorter than the peak wavelength of the emission spectrum of the light emitting element, the light emission of the light emitting element can be appropriately detected. Can be done. Further, in the inspection apparatus according to one aspect of the present invention, the wavelength of the excitation light is longer than the absorption edge wavelength of the target substrate. This prevents light from being absorbed by the substrate and makes it difficult for excitation light to reach the light emitting element, and also prevents the substrate from being excited by the excitation light, allowing light other than light emitted by the light emitting element to be detected. This can be suppressed. As described above, according to the inspection apparatus according to one embodiment of the present invention, the light emission of the light emitting element to be measured can be appropriately acquired, and the quality of the light emitting element can be determined with high accuracy based on the light emission. .

The control unit may determine the wavelength of the excitation light to be shorter than the wavelength obtained by subtracting the full width at half maximum of the emission spectrum from the peak wavelength of the emission spectrum of the light emitting element. Thereby, the wavelength of the excitation light can be made shorter than most wavelength bands included in the emission spectrum, and the light emission from the light emitting element can be appropriately detected.

The light source section includes a white light source of excitation light and a plurality of first bandpass filters that transmit excitation light in different wavelength bands, and the control section selects one of the first bandpass filters according to the determined wavelength of the excitation light. Bandpass filters may be switched. In this way, by changing the wavelength of the excitation light by switching the bandpass filter, there is no need to provide a plurality of light sources to change the wavelength, and the device can be downsized.

The light source section may include a plurality of light sources that generate excitation light of different wavelengths, and the control section may switch between the plurality of light sources according to the determined wavelength of the excitation light. According to such a configuration, the wavelength of the excitation light can be changed with a simple device configuration without providing a plurality of bandpass filters.

The inspection device further includes a plurality of second bandpass filters that transmit light in different wavelength bands, and the control unit is configured to install the second bandpass filters on the optical path from the light emitting element to the photodetection unit according to the determined wavelength of the excitation light. The second bandpass filter used may be switched. Thereby, an appropriate second bandpass filter can be set in conjunction with the determination of the wavelength of the excitation light according to the emission color of the light emitting element. This makes it possible to smoothly set an appropriate bandpass filter for detecting light emission.

The inspection device further includes a plurality of first wavelength separation elements that separate excitation light and emission light using different wavelengths as first separation wavelengths, and the control unit controls the determination of the determined excitation light. Depending on the wavelength, the first wavelength separation element installed in the optical path from the light source to the light emitting element and from the light emitting element to the photodetector may be switched. Thereby, an appropriate first wavelength separation element can be set in conjunction with the determination of the wavelength of excitation light according to the emission color of the light emitting element. With this, it is possible to smoothly set a wavelength separation element appropriate for detecting light emission.

The inspection device includes a plurality of devices that use mutually different wavelengths as second separation wavelengths and separate light emission with a wavelength longer than the second separation wavelength and emission light with a wavelength shorter than the second separation wavelength using the second separation wavelength. The photodetector further includes a second wavelength separation element, and the photodetector includes a first photodetector that detects a wavelength of the emitted light that is longer than the second separated wavelength; a second photodetector that detects light emission with a short wavelength; A second wavelength separation element installed in the optical path leading to the wavelength separation element may be switched. Thereby, an appropriate second wavelength separation element can be set in conjunction with the determination of the wavelength of excitation light according to the emission color of the light emitting element. As a result, in a configuration in which two photodetectors detect the long-wavelength side light emission and the short-wavelength side light emission, it is possible to smoothly set a wavelength separation element appropriate for detecting the light emission.

The inspection device includes a plurality of second bandpass filters that transmit light in different wavelength bands, and a plurality of second bandpass filters that use different wavelengths as first separation wavelengths to separate excitation light and emission. A first wavelength separation element, which uses different wavelengths as second separation wavelengths, and uses the second separation wavelength to emit light with a wavelength longer than the second separation wavelength and emit light with a wavelength shorter than the second separation wavelength. The light source section further includes a plurality of second wavelength separation elements for separating, and the light source section has a white light source of excitation light and a plurality of first bandpass filters that transmit excitation light in mutually different wavelength bands. The photodetector includes a first photodetector that detects the emitted light having a longer wavelength than the second separated wavelength among the emitted light, and a second photodetector that detects the emitted light that has a shorter wavelength than the second separated wavelength among the emitted light. a photodetector, and the control unit selects a first bandpass filter, a second bandpass filter, a first wavelength separation element, and a second wavelength separation element according to the determined wavelength of the excitation light. The elements may be switched integrally. Thereby, each configuration suitable for detecting light emission can be set more smoothly in conjunction with the determination of the wavelength of excitation light according to the color of light emitted from the light emitting element.

An inspection method according to one embodiment of the present invention is an inspection method for inspecting an object in which a plurality of light emitting elements are formed on a substrate, and includes a step of inputting information regarding the emitted light color of the light emitting elements; a step of deriving the absorption edge wavelength of the target substrate and the peak wavelength of the emission spectrum of the light emitting element based on , and controlling the light source unit so that the wavelength is shorter than the peak wavelength.

According to the present invention, it is possible to determine the quality of a light emitting element with high accuracy.

FIG. 3 is a calibration diagram of the inspection device according to the embodiment of the present invention. It is a figure explaining an emission spectrum. It is a flow chart of an inspection method.

Embodiments of the present invention will be described in detail below with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations will be omitted.

FIG. 1 is a configuration diagram of an inspection apparatus 1 according to this embodiment. The inspection device 1 is a device that inspects a sample S (object). The sample S is, for example, a semiconductor device in which a plurality of light emitting elements are formed on a substrate. Examples of the light emitting element include an LED, a mini LED, a μLED, an SLD element, a laser element, and a vertical laser element (VCSEL). Note that in this embodiment, the substrate of sample S includes not only a layer of silicon or sapphire, but also a layer of GaN or the like formed on the layer by epitaxial growth. The inspection apparatus 1 determines the quality of each light emitting element by observing photoluminescence (specifically, light emission such as fluorescence) of a plurality of light emitting elements formed in the sample S. It is conceivable that the quality of the light emitting element is determined by, for example, probing (ie, based on electrical characteristics). However, it is physically difficult to perform probing, which involves placing a needle against a minute LED such as a μLED, for measurement. In this regard, the method for determining the quality of light-emitting elements based on photoluminescence according to the present embodiment can determine the quality of light-emitting elements by acquiring fluorescence images, so it is possible to evaluate the quality of light-emitting elements in large quantities without being bound by physical constraints. It is possible to efficiently determine pass/fail.

As shown in FIG. 1, the inspection apparatus 1 includes a chuck 11, an XY stage 12, a light source section 20, a plurality of wavelength separation elements 40 (first wavelength separation elements), an objective lens 51, and a Z stage. 52, a plurality of wavelength separation elements 60 (second wavelength separation elements), imaging lenses 71, 72, cameras 81 (photodetection section, first photodetector), 82 (photodetection section, second a photodetector), a dark box 90, a control device 100 (control unit), a monitor 110, a keyboard 120 (input unit), and a plurality of bandpass filters 202 and 203 (second bandpass filters), respectively. , is equipped with. The dark box 90 accommodates components other than the control device 100, the monitor 110, and the keyboard 120 among the components described above, and is provided to avoid the influence of external light on each of the components contained therein. There is. Note that each component housed in the dark box 90 may be mounted on an anti-vibration table in order to improve the quality of images captured by the cameras 81 and 82 (improve image quality and prevent image position shift). good.

The chuck 11 is a holding member that holds the sample S. The chuck 11 holds the sample S by vacuum suctioning the substrate of the sample S, for example. The XY stage 12 is a stage that moves the chuck 11 holding the sample S in the XY direction (front-back and left-right directions), that is, in the direction along the mounting surface of the sample S on the chuck 11. The XY stage 12 moves the chuck 11 in the XY directions under the control of the control device 100 so that each of the plurality of light emitting elements is sequentially irradiated with excitation light. Note that the inspection device 1 may further include a rotation stage (Θ stage, not shown). Such a rotation stage may be provided, for example, above the XY stage 12 and below the chuck 11, or may be provided integrally with the XY stage 12. The rotation stage is used to precisely align the vertical and horizontal positions of the sample S. By providing the rotation stage, it is possible to shorten the time for positioning, etc., and to shorten the total time for data processing.

The light source section 20 generates excitation light that is irradiated onto the light emitting element. The light source section 20 has one excitation light source 21 and an optical system 22. The excitation light source 21 is a light source that generates excitation light to be irradiated onto the sample S and irradiates the sample S with the excitation light. The excitation light source 21 may be a white light source that can generate light including a wavelength that excites the light emitting element of the sample S, for example. Examples of the white light source include an LED, a laser, a halogen lamp, a mercury lamp, a D2 lamp, and a plasma light source. Note that the inspection device 1 may further include a sensor that monitors illumination brightness in order to keep the brightness of the excitation light emitted from the excitation light source 21 constant.

The optical system 22 includes an optical fiber cable 22a, a light guide lens 22b, and a plurality of bandpass filters 22c (first bandpass filters). The optical fiber cable 22a is a light guiding optical fiber cable connected to the excitation light source 21. As the optical fiber cable 22a, for example, a polarization maintaining fiber or a single mode fiber can be used. The light guide lens 22b is, for example, a single or composite convex lens, and guides the excitation light that has arrived via the optical fiber cable 22a toward the wavelength separation element 40.

The plurality of bandpass filters 22c are filters that transmit excitation light in different wavelength bands. That is, the plurality of bandpass filters 22c filter different wavelength bands. Only one of the plurality of bandpass filters 22c is selected and set by the control device 100, which will be described later. The bandpass filter 22c is provided between the light guide lens 22b and the wavelength separation element 40 in order to prevent the wavelength of the excitation light emitted from the excitation light source 21 from changing over time.

The plurality of wavelength separation elements 40 use mutually different wavelengths as first separation wavelengths and separate excitation light and emission light using the first separation wavelengths. That is, the plurality of wavelength separation elements 40 have different separation wavelengths that serve as a reference for separating excitation light and emission light. Only one of the plurality of wavelength separation elements 40 is selected and set by the control device 100 described later. The wavelength separation element 40 is a dichroic mirror made using an optical material such as a dielectric multilayer film, and reflects light of a specific wavelength while transmitting light of other wavelengths. Specifically, the wavelength separation element 40 reflects the excitation light toward the objective lens 51, and also reflects photoluminescence (specifically, light emission such as fluorescence) from the light emitting element, which is light in a wavelength band different from that of the excitation light. It is configured to transmit in the direction of the wavelength separation element 60.

The objective lens 51 is configured to observe the sample S, and focuses the excitation light guided by the wavelength separation element 40 onto the sample S. The Z stage 52 performs focus adjustment by moving the objective lens 51 in the Z direction (vertical direction), that is, in a direction intersecting the mounting surface of the sample S on the chuck 11.

The plurality of wavelength separation elements 60 use mutually different wavelengths as second separation wavelengths, and use the second separation wavelengths to separate light emission with a wavelength longer than the second separation wavelength and emission with a wavelength shorter than the second separation wavelength. Separate. That is, the plurality of wavelength separation elements 60 have different separation wavelengths, which serve as a reference for separating the long-wavelength side light emission and the low-wavelength side light emission. Only one of the plurality of wavelength separation elements 60 is selected by the control device 100, which will be described later, and is set by switching. The wavelength separation element 60 is a dichroic mirror made using an optical material such as a dielectric multilayer film, and reflects light of a specific wavelength while transmitting light of other wavelengths. This dichroic mirror may not only have a characteristic in which the transmittance (reflectance) changes sharply with respect to the wavelength, but also a characteristic in which the transmittance (reflectance) with respect to the wavelength changes gradually with a width of about 100 nm. . The wavelength separation element 60 is configured so as not to transmit (reflect) the emitted light having a wavelength shorter than the second separation wavelength, but to transmit the fluorescence having a wavelength longer than the second separation wavelength. The short-wavelength light that is reflected by the wavelength separation element 60 is, for example, light with a wavelength included in the normal emission spectrum (emission with the original emission wavelength), and the long-wavelength fluorescence that is transmitted by the wavelength separation element 60 is included in the normal emission spectrum. This is light emission with wavelengths that are not included (light emission on the long wavelength side). Note that the original emission wavelength may be, for example, a wavelength known in advance from the specifications of the light emitting element, or may be a wavelength at which the intensity of fluorescence from the light emitting element is actually measured using a spectrometer. In addition, in detail, it is considered that the wavelength separation element 60 transmits a part of the emitted light having a wavelength shorter than the second separated wavelength and reflects a part of the emitted light having a longer wavelength than the second separated wavelength. However, in general, it reflects light emission with a wavelength shorter than the second separation wavelength and transmits light emission with a longer wavelength than the second separation wavelength. It reflects light emission with a wavelength shorter than the separation wavelength, and transmits light emission with a wavelength longer than the second separation wavelength.'' Light emission with a wavelength longer than the second separation wavelength (light emission on the long wavelength side) reaches the imaging lens 71 via the wavelength separation element 60. Light emission with a wavelength shorter than the second separation wavelength (light emission with the original emission wavelength) reaches the imaging lens 72 via the wavelength separation element 60. Note that the wavelength separation element 60 does not necessarily have to be a dichroic mirror, and may be realized, for example, by a combination of a half mirror and bandpass filters 202 and 203.

The plurality of bandpass filters 202 are filters that transmit light in different wavelength bands. That is, the plurality of bandpass filters 202 filter different wavelength bands. Only one of the plurality of bandpass filters 202 is selected and set by the control device 100, which will be described later. The bandpass filter 202 is provided between the wavelength separation element 60 and the camera 81 in order to prevent unnecessary light emission on the long wavelength side. The plurality of bandpass filters 203 are filters that transmit light in different wavelength bands. That is, the plurality of bandpass filters 203 filter different wavelength bands. Only one of the plurality of bandpass filters 203 is selected by the control device 100, which will be described later, and is set by switching. The bandpass filter 203 is provided between the wavelength separation element 60 and the camera 82 in order to prevent the long wavelength emission from being mixed in due to surface reflection of the wavelength separation element 60 when measuring the emission of the short wavelength side.

The imaging lens 71 is a lens that forms an image of the emitted light on the longer wavelength side and guides the emitted light to the camera 81 . The camera 81 is an imaging unit that images the light emitted from the sample S. More specifically, the camera 81 images and detects the light emitted from the light emitting element with a wavelength longer than the above-mentioned second separation wavelength (emission on the long wavelength side). The camera 81 outputs a light emission image on the long wavelength side, which is the imaging result, to the control device 100. The camera 81 is, for example, an area image sensor such as a CCD or MOS. Further, the camera 81 may be configured by a line sensor or a TDI (Time Delay Integration) sensor.

The imaging lens 72 is a lens that forms an image of the light emitted at the original emission wavelength and guides the light emission to the camera 82 . The camera 82 is an imaging unit that images the light emitted from the sample S. More specifically, the camera 82 detects light emitted from the light emitting element at a wavelength shorter than the above-mentioned second separation wavelength and included in the normal emission spectrum ES of the light emitting element (original emission wavelength). (light emission) is imaged and detected. The camera 82 outputs a light emission image of the original light emission wavelength, which is an imaging result, to the control device 100. The camera 82 is, for example, an area image sensor such as a CCD or MOS. Further, the camera 82 may be configured by a line sensor or a TDI sensor.

The control device 100 is a computer, and physically includes a memory such as a RAM and a ROM, a processor (arithmetic circuit) such as a CPU, a communication interface, and a storage unit such as a hard disk. Examples of the control device 100 include a personal computer, a cloud server, a smart device (smartphone, tablet terminal, etc.), and the like. The control device 100 functions by executing a program stored in a memory using a CPU of a computer system. Control device 100 controls XY stage 12, excitation light source 21, Z stage 52, and cameras 81 and 82. Specifically, the control device 100 adjusts the irradiation area of the excitation light (the irradiation area on the sample S) by controlling the XY stage 12. The control device 100 performs focus adjustment regarding the excitation light by controlling the Z stage 52. The control device 100 controls the excitation light source 21 to adjust the emission of excitation light and adjust the wavelength, amplitude, etc. of the excitation light. The control device 100 controls the cameras 81 and 82 to make adjustments related to the acquisition of light emission images.

Further, the control device 100 determines the quality of the light emitting element of the sample S based on the light emission images captured by the cameras 81 and 82. The control device 100 determines the quality of the light emitting element based on the long wavelength side emission image acquired by the camera 81 and the emission image at the original emission wavelength acquired by the camera 82. For example, the control device 100 determines the quality of the light emitting element based on the light emission image of the original light emission wavelength acquired by the camera 82, and after this determination, the control device 100 displays the light emitting element that is determined to be good in the determination by the camera 81. The quality is determined based on the long-wavelength side emission image obtained by.

The control device 100 first identifies the positions of the light emitting elements based on the light emission image, and identifies the light emitting area of each light emitting element. The position of the light emitting element is determined, for example, by converting the position in the light emission image and the position of the XY stage 12. Note that the control device 100 may acquire a pattern image of the entire sample S in advance, and recognize (specify) the position of the light emitting element from the pattern image or the light emission image. Then, the control device 100 derives the average brightness within the light emitting area of each light emitting element based on the light emission image of the original light emission wavelength, and links the address position and brightness (average brightness within the light emitting area) for each light emitting element. . The control device 100 derives an evaluation index from absolute brightness and relative brightness for each address (each light emitting element). Relative brightness is the brightness ratio of the light emitting element to be derived to the average brightness of a light emitting element group including the light emitting element to be derived and the light emitting elements around the light emitting element. For example, the control device 100 derives the evaluation index from the product of absolute brightness and relative brightness. Alternatively, the control device 100 derives the evaluation index from the product of the absolute brightness and the nth power of the relative brightness (n is a natural number, for example, 2). The control device 100 derives the evaluation index described above for each light emitting element included in the same light emission image. Furthermore, the control device 100 acquires a new luminescence image (a luminescence image of the original emission wavelength) by changing the irradiation area, and derives an evaluation index for each light-emitting element included in the luminescence image. When the control device 100 derives the evaluation index for all the light emitting elements, it sorts the light emitting elements in descending order of the evaluation index. When sorting is performed, it can be seen that the evaluation index rapidly decreases after a certain point (change point). For example, using such a change point as a threshold, the control device 100 determines a light emitting element whose evaluation index is equal to or greater than the threshold as a good product (good pixel), and a light emitting element smaller than the threshold as a defective product (defective pixel). Good too. Note that the threshold value can be determined by, for example, using a reference semiconductor device for determining the threshold value in advance, and determining the quality of the light emitting element based on fluorescence (photoluminescence) and the quality determination result based on probing (the quality determination result based on electrical characteristics). ) may be determined by comparing.

Furthermore, the control device 100 detects bright spots (light-emitting spots) in the light-emitting area of each light-emitting element based on the long-wavelength side light emission image, and links the address position and the number of bright spots for each light-emitting element. Such a bright spot (light emission spot) on the longer wavelength side than the normal emission spectrum is an abnormal light emission location. Then, the control device 100 determines whether the light emitting element determined to be good in the quality determination based on the light emission image of the original light emission wavelength described above contains a certain number or more of bright spots in the light emission image of the long wavelength side. A light emitting element that does not contain a certain number of bright spots or more is determined to be a good product (good pixel), and a light emitting element that contains a certain number or more bright spots is determined to be a defective product (defective pixel). In such an example, even if a light emitting element is originally determined to be a good product based on a light emission image at a light emission wavelength, it may be determined to be a defective product based on a fluorescence image at a longer wavelength.

The control device 100 determines whether the light emitting element is good or not based on the light emission image of the original light emission wavelength acquired by the camera 82, and then determines whether the light emitting element is defective in the determination. The quality may be determined based on the emission image on the long wavelength side. Further, the control device 100 may perform quality determination for all light emitting elements based on long wavelength side emission images. In this way, the control device 100 may perform a pass/fail determination based on the long wavelength side emission image only for the light emitting element that was determined to be good based on the emission image of the original emission wavelength, or may perform a quality judgment based on the emission image of the long wavelength side. Only those light emitting elements determined to be defective based on the image may be judged to be pass/fail based on the long-wavelength emission image, or all light emitting elements may be judged to be defective, regardless of the pass/fail judgment result based on the emission image at the original emission wavelength. A quality determination may be made based on a light emission image on the long wavelength side.

The control device 100 outputs the quality determination result of each light emitting element. The quality determination result is displayed on the monitor 110, for example. The control device 100 may also identify a defective location (for example, a bright spot on the longer wavelength side) in the light emitting element, and output the location of the defective location (output it so that it is displayed on the monitor 110). .

The control device 100 performs predetermined control according to information regarding the emitted light color of the light emitting element in order to perform the above-described quality judgment with higher accuracy. Information regarding the emitted light color of the light emitting element is received by a user's input using the keyboard 120, and is input to the control device 100, for example.

The control device 100 determines the wavelength of the excitation light based on the information regarding the emitted light color received by the keyboard 120. Specifically, the control device 100 sets the wavelength of the excitation light to a wavelength that is longer than the absorption edge wavelength of the substrate of the sample S and shorter than the peak wavelength of the emission spectrum of the light emitting element specified from the information regarding the emission color. decided on. The absorption edge wavelength of a substrate is the longest wavelength at which light absorption occurs in the substrate. The absorption edge wavelength of the substrate is determined by the bandgap of the base material. Light with a wavelength longer than the absorption edge wavelength of the substrate is transmitted through the substrate. As described above, the substrate of sample S includes not only a layer of silicon or sapphire, but also a layer of GaN or the like formed on the layer by epitaxial growth. By making the wavelength of the excitation light longer than the absorption edge wavelength of the substrate, excitation of the substrate by the excitation light (occurrence of light emission from the substrate) is suppressed. Further, by setting the wavelength of the excitation light to be shorter than the peak wavelength of the emission spectrum, the light emitting element can be appropriately excited and light emitted from the light emitting element can be appropriately acquired. More specifically, the control device 100 sets the wavelength of the excitation light to a wavelength shorter than the wavelength obtained by subtracting the full width at half maximum of the emission spectrum from the peak wavelength of the emission spectrum of the light emitting element (taking the difference in the full width at half maximum). decide.

FIG. 2 is a diagram illustrating the emission spectrum under each condition. In FIG. 2, the horizontal axis represents wavelength, and the vertical axis represents brightness (A.U.). In addition, in FIG. 2, the thin broken line represents the emission spectrum of sample S when the wavelength of excitation light is 370 nm, the thick dashed line represents the emission spectrum of sample S when the wavelength of excitation light is 355 nm, and the solid line represents the emission spectrum of sample S when the wavelength of excitation light is 355 nm. The emission spectra of sample S when flowing are shown. When the sample S is commercialized and used, electricity is applied to the light emitting element. Therefore, even when determining the quality of a light emitting element by irradiation with excitation light, it is preferable that the emission spectrum is similar to the emission spectrum when electricity is passed through the light emitting element. Note that the level of luminance of light emission is actually different when the light emitting element is excited with excitation light and when electricity is passed through it, but the shape of the emission spectrum is important here, so the difference in the level of luminance is are adjusted and illustrated as appropriate.

Assume now that the light emitting element of the sample S to be observed is a blue LED (emission color is blue). In this case, the emission wavelength width of the light emitting element is, for example, 420 nm to 480 nm. Further, it is assumed that the absorption edge wavelength of the Gan substrate of sample S is 365 nm. Under these conditions, as shown in Figure 2, when the wavelength of the excitation light is set to 355 nm, that is, when the wavelength of the excitation light is made shorter than the absorption edge wavelength of the substrate, the emission spectrum (Figure 2 "PL(355)") is significantly different from the emission spectrum ("EL" in FIG. 2) when electricity is passed through the light emitting element. This is thought to be due to the fact that the wavelength of the excitation light was made shorter than the absorption edge wavelength of the substrate, thereby being affected by light emission from the substrate. On the other hand, as shown in FIG. 2, when the wavelength of the excitation light is 370 nm, that is, when the wavelength of the excitation light is made longer than the absorption edge wavelength of the substrate, the emission spectrum ("PL" in FIG. 2) (370)'') is similar to the emission spectrum ("EL" in FIG. 2) when electricity is passed through the light emitting element. In this way, by making the wavelength of the excitation light longer than the absorption edge wavelength of the substrate of the sample S, an appropriate emission spectrum can be obtained without being affected by light emission from the substrate. In the above example, the wavelength of the excitation light is preferably in the range of 365 nm to 420 nm, which is the absorption edge wavelength of the substrate. Note that it is preferable that the wavelength of the excitation light be as long as possible within the above range because the middle region of the quantum well will not be excited and the contrast in the intensity of light emission will be increased. Note that, for example, in the case where the light emitting element is a green LED (emission color is green), the emission wavelength width of the light emitting element is, for example, 490 nm to 550 nm. In this case, the wavelength of the excitation light is preferably in the range of 365 nm to 490 nm, which is the absorption edge wavelength of the substrate.

The control device 100 controls the light source section 20 so that excitation light of the determined wavelength is generated. Specifically, the control device 100 selects the bandpass filter 22c that transmits the excitation light of the determined wavelength so that the excitation light of the determined wavelength is emitted from the light source section 20 and irradiated to the light emitting element, The bandpass filter 22c is installed on the optical path from the light source section 20 to the wavelength separation element 40. In this way, the control device 100 switches the bandpass filter 22c according to the determined wavelength of the excitation light. Note that the inspection device 1 may include a plurality of excitation light sources 21 that generate excitation lights of mutually different wavelengths. In this case, the excitation light source 21 may be composed of a plurality of light sources capable of generating mutually different monochromatic lights, and the plurality of light sources are, for example, LEDs, SLDs, lasers, and the like. In this case, the control device 100 selects the excitation light source 21 capable of generating excitation light of the determined wavelength and generates the excitation light, similar to the mode in which the bandpass filter 22c is switched and set as described above. Therefore, excitation light of a desired wavelength can be generated. That is, the control device 100 may switch the plurality of excitation light sources 21 according to the determined wavelength of the excitation light.

The control device 100 may switch the bandpass filter 202 installed in the optical path from the light emitting element to the camera 81 according to the determined wavelength of the excitation light. In this case, the control device 100 selects the bandpass filter 202 that can prevent unnecessary light emission on the long wavelength side, taking into consideration the emission color of the light emitting element related to determining the wavelength of the excitation light, for example. Further, the control device 100 may switch the bandpass filter 203 installed in the optical path from the light emitting element to the camera 82 according to the determined wavelength of the excitation light. In this case, the control device 100 considers the emission color of the light emitting element related to the determination of the wavelength of the excitation light, for example, and selects a band that can prevent the long wavelength side emission from being mixed in the measurement of the short wavelength side emission. Select pass filter 203.

The control device 100 may switch the wavelength separation element 40 installed in the optical path from the light source section 20 to the light emitting element and from the light emitting element to the cameras 81 and 82, depending on the determined wavelength of the excitation light. In this case, the control device 100 reflects the excitation light in the direction of the objective lens 51 and transmits the emitted light in the direction of the wavelength separation element 60, taking into consideration the emission color of the light emitting element and the wavelength of the excitation light, for example. A separation element 40 is selected.

The control device 100 may switch the wavelength separation element 60 installed on the optical path from the light emitting element to the cameras 81 and 82, depending on the determined wavelength of the excitation light. In this case, the control device 100 can appropriately separate the light emission at the original emission wavelength and the emission at the long wavelength side, taking into account the emission color of the light emitting element, for example (the second separation wavelength is appropriate). A wavelength separation element 60 is selected.

Note that the control device 100 may integrally switch the bandpass filter 22c, the bandpass filters 202 and 203, the wavelength separation element 40, and the wavelength separation element 60 according to the determined wavelength of the excitation light. That is, the control device 100 may simultaneously switch the above-described bandpass filter 22c, bandpass filters 202, 203, wavelength separation element 40, and wavelength separation element 60 in conjunction with the determination of the wavelength of the excitation light. .

Next, the inspection method will be explained with reference to FIG. FIG. 3 is a flowchart of an inspection method performed using the inspection apparatus 1. The inspection method is an inspection method for inspecting a sample S in which a plurality of light emitting elements are formed on a substrate.

As shown in FIG. 3, first, information regarding the emitted light color of the light emitting element is input from the keyboard 120 (step S1, input step). The inspection device 1 receives input of information regarding the emitted light color.

Subsequently, the inspection device 1 determines the wavelength of the excitation light based on the information regarding the emission color (step S2). Specifically, the inspection apparatus 1 derives the absorption edge wavelength of the substrate of the sample S and the peak wavelength of the emission spectrum of the light emitting element based on the information regarding the emission color (derivation step).

Subsequently, the inspection apparatus 1 sets the bandpass filter 22c of the light source section 20 to match the determined wavelength of the excitation light (step S3). That is, the inspection apparatus 1 controls the light source section 20 so that the wavelength of the excitation light is longer than the absorption edge wavelength of the substrate and shorter than the peak wavelength of the emission spectrum (controlling step).

Next, the inspection device 1 integrally sets the bandpass filter 22c, bandpass filters 202, 203, wavelength separation element 40, and wavelength separation element 60 according to the determined wavelength of the excitation light (step S4). .

Subsequently, the inspection device 1 irradiates the light emitting element with excitation light and detects light emission (fluorescence) from the light emitting element (step S5). Then, the inspection device 1 determines the quality of the light emitting element based on the light emitted from the light emitting element (step S6).

Next, the effects of the inspection device 1 according to this embodiment will be explained.

The inspection apparatus 1 is an inspection apparatus for inspecting a sample S in which a plurality of light emitting elements are formed on a substrate, and includes a light source unit 20 that generates excitation light to be irradiated to the light emitting elements, and a light source unit 20 that generates excitation light that is irradiated to the light emitting elements, and Cameras 81 and 82 detect light emission from the elements; a keyboard 120 receives input of information regarding the emission color of the light emitting element; and a wavelength of the excitation light is determined based on the information regarding the emission color received by the keyboard 120; a control device 100 that controls the light source unit 20 so that excitation light of A wavelength shorter than the peak wavelength of the emission spectrum of the light emitting element is determined as the wavelength of the excitation light.

In such an inspection apparatus 1, input of information regarding the emission color of the light emitting element is accepted, and the wavelength of the excitation light is set to be shorter than the peak wavelength of the emission spectrum of the light emitting element. In this way, the wavelength of the excitation light is determined according to the emission color of the light emitting element, and by making the wavelength of the excitation light shorter than the peak wavelength of the emission spectrum of the light emitting element, the light emission of the light emitting element can be appropriately detected. Can be done. Further, in the inspection apparatus according to one aspect of the present invention, the wavelength of the excitation light is longer than the absorption edge wavelength of the substrate of the sample S. This prevents light from being absorbed by the substrate and making it difficult for excitation light to reach the light emitting element. Furthermore, it is possible to suppress the substrate from being excited by the excitation light, and to suppress the detection of light other than the light emitted from the light emitting element. As described above, according to the inspection apparatus 1, the light emitted from the light emitting element to be measured can be appropriately acquired, and based on the light emitted, the quality of the light emitting element can be determined with high accuracy.

The control device 100 may determine the wavelength of the excitation light to be shorter than the wavelength obtained by subtracting the full width at half maximum of the emission spectrum from the peak wavelength of the emission spectrum of the light emitting element. Thereby, the wavelength of the excitation light can be made shorter than most wavelength bands included in the emission spectrum, and the light emission from the light emitting element can be appropriately detected.

The light source unit 20 includes a white light source of excitation light and a plurality of bandpass filters 22c that transmit excitation light in different wavelength bands, and the control device 100 selects the bandpass filters according to the determined wavelength of the excitation light. 22c may be switched. In this way, by changing the wavelength of the excitation light by switching the bandpass filter 22c, it is not necessary to provide a plurality of excitation light sources 21 to change the wavelength, and the inspection apparatus 1 can be downsized.

The light source unit 20 includes a plurality of excitation light sources 21 that generate excitation light of different wavelengths, and the control device 100 may switch among the plurality of excitation light sources 21 according to the determined wavelength of the excitation light. According to such a configuration, the wavelength of the excitation light can be changed with a simple device configuration without providing a plurality of bandpass filters 22c.

The inspection device 1 further includes a plurality of bandpass filters 202 and 203 that transmit light in different wavelength bands, and the control device 100 controls the optical path from the light emitting element to the camera 81 according to the determined wavelength of the excitation light. The bandpass filter 202 installed and the bandpass filter 203 installed on the optical path from the light emitting element to the camera 82 may be switched. Thereby, appropriate bandpass filters 202 and 203 can be set in conjunction with the determination of the wavelength of excitation light according to the emission color of the light emitting element. This makes it possible to smoothly set bandpass filters 202 and 203 appropriate for detecting light emission.

The inspection device 1 further includes a plurality of wavelength separation elements 40 that separate excitation light and emission using different wavelengths as first separation wavelengths, and the control device 100 controls how the determined excitation light is separated. Depending on the wavelength, the wavelength separation element 40 installed in the optical path from the light source section 20 to the light emitting element and from the light emitting element to the cameras 81 and 82 may be switched. Thereby, an appropriate wavelength separation element 40 can be set in conjunction with the determination of the wavelength of excitation light according to the emission color of the light emitting element. With this, it is possible to smoothly set the appropriate wavelength separation element 40 for detecting light emission.

The inspection device 1 includes a plurality of inspection apparatuses that use mutually different wavelengths as second separation wavelengths and use the second separation wavelengths to separate light emission with a wavelength longer than the second separation wavelength and light emission with a wavelength shorter than the second separation wavelength. A camera 81 which further includes a wavelength separation element 60 and which detects the light emission having a wavelength longer than the second separation wavelength among the light emission, and a camera 82 which detects the light emission having a wavelength shorter than the second separation wavelength among the light emission. The control device 100 may switch the wavelength separation element 60 installed in the optical path from the light emitting element to the cameras 81 and 82, depending on the determined wavelength of the excitation light. Thereby, an appropriate wavelength separation element 60 can be set in conjunction with the determination of the wavelength of excitation light according to the emission color of the light emitting element. With this, in a configuration in which two photodetectors detect long-wavelength and short-wavelength light, it is possible to smoothly set the wavelength separation element 60 that is appropriate for detecting light.

The control device 100 may integrally switch the bandpass filter 22c, the bandpass filters 202 and 203, the wavelength separation element 40, and the wavelength separation element 60 according to the determined wavelength of the excitation light. Thereby, each configuration suitable for detecting light emission can be set more smoothly in conjunction with the determination of the wavelength of excitation light according to the color of light emitted from the light emitting element.

DESCRIPTION OF SYMBOLS 1... Inspection device, 20... Light source part, 21... Excitation light source, 22c... Band pass filter, 40... Wavelength separation element, 60... Wavelength separation element, 81, 82... Camera, 100... Control device, 120... Keyboard, 202, 203...Band pass filter.

Claims (8)

An inspection device for inspecting an object having a plurality of light emitting elements formed on a substrate,
a light source unit that generates excitation light that is irradiated to the light emitting element;
a light detection unit that detects light emission from the light emitting element irradiated with the excitation light;
an input unit that receives information regarding the emission color of the light emitting element;
a control unit that determines the wavelength of the excitation light based on information regarding the emission color received by the input unit, and controls the light source unit so that the excitation light of the wavelength is generated;
a plurality of second bandpass filters that transmit the light emission in mutually different wavelength bands ;
The control unit determines a wavelength in a range of 365 nm to 490 nm as the wavelength of the excitation light ,
In the inspection device, the control unit switches the second bandpass filter installed on the optical path from the light emitting element to the photodetection unit according to the determined wavelength of the excitation light. The inspection device according to claim 1, wherein the control unit determines a wavelength in a range of 365 nm to 490 nm as the wavelength of the excitation light when the information regarding the emission color received by the input unit is green. The inspection device according to claim 1, wherein the control unit determines a wavelength in a range of 365 nm to 420 nm as the wavelength of the excitation light when the information regarding the emission color received by the input unit is blue. The light source section includes a white light source for the excitation light and a plurality of first bandpass filters that transmit the excitation light in different wavelength bands,
4. The inspection device according to claim 1, wherein the control unit switches the first bandpass filter according to the determined wavelength of the excitation light. The light source section has a plurality of light sources that generate the excitation light of mutually different wavelengths,
4. The inspection apparatus according to claim 1, wherein the control unit switches the plurality of light sources according to the determined wavelength of the excitation light. further comprising a plurality of first wavelength separation elements that separate the excitation light and the emission using different wavelengths as first separation wavelengths,
The control section controls the first wavelength separation element, which is installed in an optical path from the light source section to the light emitting element and from the light emitting element to the photodetection section, according to the determined wavelength of the excitation light. The inspection device according to any one of claims 1 to 5 , wherein the inspection device switches. A plurality of second separation wavelengths having different wavelengths as second separation wavelengths and separating light emission with a wavelength longer than the second separation wavelength and light emission with a wavelength shorter than the second separation wavelength by the second separation wavelength. further comprising a wavelength separation element,
The photodetector includes a first photodetector that detects a wavelength of the emitted light that is longer than the second separated wavelength, and a first photodetector that detects the emitted light that has a wavelength shorter than the second separated wavelength of the emitted light. a second photodetector for detecting,
The control unit controls the second wavelength separation element installed in the optical path from the light emitting element to the first photodetector and the second photodetector, depending on the determined wavelength of the excitation light. The inspection device according to any one of claims 1 to 6 , wherein the inspection device switches. a plurality of second bandpass filters that transmit the emitted light in different wavelength bands; and a plurality of second bandpass filters that separate the excitation light and the emitted light by the first separation wavelength, each having a different wavelength as a first separation wavelength. 1 wavelength separation element, different wavelengths from each other are used as second separation wavelengths, and the second separation wavelength enables emission of light with a wavelength longer than the second separation wavelength and emission of light with a wavelength shorter than the second separation wavelength. further comprising a plurality of second wavelength separation elements that separate the
The light source section includes a white light source for the excitation light and a plurality of first bandpass filters that transmit the excitation light in different wavelength bands,
The photodetector includes a first photodetector that detects a wavelength of the emitted light that is longer than the second separated wavelength, and a first photodetector that detects the emitted light that has a wavelength shorter than the second separated wavelength of the emitted light. a second photodetector for detecting,
The control unit integrates the first bandpass filter, the second bandpass filter, the first wavelength separation element, and the second wavelength separation element according to the determined wavelength of the excitation light. The inspection device according to any one of claims 1 to 7 , wherein the inspection device switches automatically.

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